Torque-indicating wrench



w. c. RRESS TORQUE- INDICATING WRENCH Aug. 11.1939.

Filed March 18,

INVENTOR lil Patented Aug. l, 1939v PATENT ort-fici:

2,167,720 v fi'oRQUE-INDlcAfrlNG WRENCH'- iWillen-11C. Kress, Kenmore, N. YL, assigner 'td' J. H. Williams & C0., Bualo, Y., a corpora?- tion of New York ,Application Manch 18, i937, Serial No.,J131,5f47

i claim. (ci. 265-1) y My present invention relatesv to a torque-indicating or measuring wrench, and aims to provide certain improvements thereon.

Torque-indicating or measuring wrenches have heen heretofore proposedv for indicating `,applied predetermined measured force in tightening capl screws, bolts, nuts and the like in the various applications 'thereof and'haverecently found particular lfavor in the tightening oi cap-screws and holts for holding down the heads oigengine cylinder blocks. These cylinder bloei: heads are usually made of aluminum and are easily distortedxif the cap-screwsv or hold down bolts are not `uniformly tightened, said cylinder heads are frequently ruptured where the cap-screws or bolts are to be severely tightened. In fact, many iailures in motor rebuilding and cylinder loloclr rehoring'johs have heen definitely traced to the uneven tightening oi the cylinder head studs.

-The torque-indicating or measuring wrenches heretofore proposed-with which I 'am familiar have either used springs or fluid pressure means for resisting and measuring the torque applied to the elements heing rotated, and all are either complicated in construction 'or cumbersome and unwieldy in use.` l l t My lpresent invention provides a torque indicating wrench consisting of but a few parts and 's devoid of springs or fluidpressure means, and.

. is based on the principle of measuring the deflective torque on the shank or operating handle of the wrench when applying turning'for'ce to a4 rotatable element. 1n its preferred construction, my torque indicating wrench comprises a handle provided at one end with means lfor driving or rotating a cap-screw, bolt. nut, or the like, and has' attached to said driving means a rigid arm extending in substantially parallel spaced relation to the handle and having at its opposite end means which operate in conjunction with means carried by and movable with the handle Afor indicating the delective torque or the handle under operating load. More specifically. the wrench comprises a gauge mounted on the handle and the rigid'arm is made ofless length than the handle and provided adjacent the gauge with an oblique shoulder upon which a follower of the gauge is adapted to ride and thereby operate the indicating mechanisml of the gauge as the wrench handle is subjected to ydeilecti've torque when applying turning force to a rotative element. A preferred embodiment of my invention is illustrated in the accompanying drawing wherein- Fig. 1 is a. top plan view'ot my torque-indicating wrench.

Fig. 2 is a side elevation of the wrench shown in Fig. l. d t ,Y

,lEigs.` 3 and d yare transverse sections taken along the planes of the lines 3--3 and 4 4 respectively oi Fig. 2. l f1 Referring to thedrawing, the torque-indicating wrench may. beLsaid to consist of but three parts, namely, a handlev tu; a rigid arm il, and

an indicating gauge c1112K Thefhndle" it at one vend is `ilxedly.connected to a driving headv tu llil which' omits under sideis provldedwith a square Ation it, which may be knurled or otherwise p'rovided with asurface which will promote the grip- J ping engagement thereof. Mounted on thefhan- 20 ,dle. intermediate its ends, and preferably in proximity to the gripping end I6, is a bracket ill upon which is mounted the dial gauge l2. Preferably the wrench handle will he made of steel and carefully ground to size and specially heat treated and g5.

hardened to insure uniformity thereof. l

Therigid arm li is .of less length than the handie and isamxed at one end Il to the top of theA driving head i3 so as to be movable therewith as a unit and extends in overlying spaced substan- 30 tiyailyparallel relation to the handle I0 and has its other end IB which is free, disposed 'adjacent the gauge i2. Intermediate the ends the rigid arm l l is of larcuate cross section. as best shown in Figs. 2 and 4, and adjacent its free end I8 is' 35 formed with a shoulder orat face i9 which ex'- tends obliquely t'o the longitudinal center line of the arm.

The gauge i 2 is rigidly supported upon the handle Ill so that thegauge plunger 20 which is guid- 40 ed for ldngitudinal movement in the tubular pro iection 20" of the gauge housing will have its axis substantially coincident with the vertical plane passing through the axis of the handle I0. The free end of the plunger 2U is provided with a fol- 45 lower 2|, preferably in the form of a steel ball mounted for free rolling movement within its bearing l 2l' mounted on the plunger 20 and adapted to ride over the oblique surface i9 at then-ee end ofthe arm Il. If desired, therarm `50 motion-magnifying means (not shown) y which will multiply the movement of the plunger 20 so as to give a larger indication of the pointer 23 on the dial l24,

In the use of the wrench hereinbefore described, the shank I4 will engage within and hold a socket member, (not shown) in assembled relation on the driving head. Upon engaging such socket with the head of a cap-screw, bolt, nut or the like, it will be apparent that by gripping the handle at I6 and moving it through an arc with the socket head as a pivot, the cap-screw, bolt or nut will be rotated and thereby fastened onto its complementary part. As the rotatable element, namely, the cap-screw, bolt or nut', is brought up into tightened relation with its co-operating part, it

`will be apparent that the handle I will ex or be deflected under the force of tightening the rotatable element.' This deflection in the handle, however, is not imparted to the rigid arm I I, and hence as the arm I0 flexes in moving the handle in a clockwise direction, the follower 2| on the gauge plunger will ride over the oblique face I9, thus moving the plunger inwardly ywith respect to the gauge housing and said movement will be multiplied and indicated by the pointer 23 on the dial 24. The inch pound or foot pound deilective torque of the wrench can be obtained by converting the indicated dial reading into inch or foot pounds by means of a special conversion table which can be supplied with each wrench. Or the oblique surface I9 upon the free end of the rigid arm II can be given such angularity on each wrench that the indicated dial reading at a given load, or deilective torque, will correspond in every case with the proper inch or foot pound torque on the conversion table; or the dial readings may be directly calibrated in inch or foot pounds.

The Wrench will be capable of giving an infinite number of accuratey readings of deflective torque so long as the handle is not stressed beyond the elastic limit of the bar stock from which it is made. Even though no conversion table is provided for converting the dial reading into inch or foot pounds, it will be apparent that the wrench will be especially useful in the automotive trade for the purpose of applying equal force to all the cap screws or bolts for tightening down the cylinder head on the engine block or for any other purpose where a uniform tightening of elements is required for agiven job by merely tightening the element to the same reading on the gauge.

It will accordingly be apparent from the foregoing description that I have provided a torqueindicating wrench of exceedingly simple and durable construction, and while I have shown but a single and preferred embodiment of my invention, I do not wish to be limited to the specific details of construction set forth, since it will be apparent to those'skilled in the art that changes in such construction may be resorted to without departing from the spirit of the invention.`r

What I claim is:

A torque-indicating wrench comprising an operating handle capable of flexing under operating load having at one end driving means for engaging and rotating a rotatable element and intermediate its ends an indicating gauge, a rigid arm xedly connected at one end to the end of the handle having the driving means and being free at its other end, said arm being of less length than the handle and extending in spaced substantially parallel relation thereto and having adjacent its free end a shoulder which is oblique to the center line of the arm 'for cooperation with a follower of the gauge for registering on said gauge the deflection of the handle under flexing load when applying turning force to a rotatable element.

WILLARD C. KRESS. 

